KR101165650B1 - Image transfer apparatus - Google Patents

Abstract

An apparatus includes a light source configured to provide a path of light and a spatial light modulator located in the path of light and configured to modulate the light source. Relay optics are configured to receive the modulated light from the spatial light modulator and to project a computer generated image to a nominal image plane. The light source is configured to illuminate the spatial light modulator with collimated light.

Description

Image transfer device {IMAGE TRANSFER APPARATUS}

This application claims priority to US Provisional Application Serial No. 60,898,168, filed Jan. 30, 2007, the specification of which is incorporated herein by reference.

The present invention relates to an image delivery device comprising an active tiling system of the type used in holography.

For example, in projection displays as used in classroom theaters, a diffused light source (eg, a high power lamp) to irradiate an electrically addressed spatial light modulator (EASLM) (high powered lamp)) is used. Projection optics are provided to focus an image of the EASLM onto a predetermined image plane, such as a projection screen or wall. Images formed by one or more EASLMs may be successively transferred to other sub-image regions of an optically addressed spatial light modulator (OASLM) that is optically addressed using an active tiling ^™ system. Active tiling systems are further described in US Pat. No. 6,437,919 and US Pat. No. 6,654,156, the specifications of which are incorporated herein by reference.

The active tiling system can include one or more EASLMs to which diffused light is irradiated. Multiple images of each EASLM are formed using replication optics and focused on a single active tiling image plane. OASLM is disposed within the active tiling image plane, and its sub-areas are selectively photosensitive, for example, by using an array of shutters or by using patterned OASLM electrodes to sequentially block certain replicated images. do. Thus, active tiling techniques allow the sub-areas of OASLM to be optically addressed in succession, resulting in an image having a very high pixel count. This system can be used for stereoscopic imaging because it allows OASLM to be recorded by a very complex Binary Fourier Transform (FT) of the final desired stereoscopic image. The image can be displayed to the viewer through appropriate FT lenses or mirror system.

Devices of the type described above require an image or images of each EASLM to be focused in the desired focal plane. Thus, the OASLM is located exactly in the active tiling image plane within the depth of focus of the active tiling optics. For example, if the active tiling system is configured to write 6.6 μm pixels, the resulting depth of focus is only about 201 μm. If the desired OASLM pixel size is reduced, the depth of focus will also decrease accordingly.

In systems configured to display very large stereoscopic images, many active tiling channels are used in parallel to produce large pixel counts in a single active tiling image plane. Although a single OASLM, or a plurality of OASLMs occupy this image plane, the entire area of the OASLM or OASLMs must be within the focal depth (eg, 20 μm) of the active tiling channels. It is to be appreciated that the active tiling channels must all be aligned with one another to create a common focal plane, and that such requirements will place significant constraints on the design and structure (and thus overall cost) of the system.

The apparatus includes a light source configured to provide a light path and a spatial light modulator located in the light path and configured to modulate the light source. Relay optics are configured to receive modulated light from the spatial light modulator and project a computer generated image to a nominal image plane. The light source is configured to irradiate collimated light to the spatial light modulator.

Various embodiments will now be described by way of example only with reference to the accompanying drawings.

1 shows an apparatus comprising an active tiling system.

2 illustrates a new image display system.

3 shows an active tiling system including a diffractive array generator (DAG).

4 illustrates an apparatus configured to provide collimated light.

5 illustrates an example method for recording information in OASLM.

1 shows an apparatus comprising an active tiling system 2 configured to generate a dynamic holographic image. The apparatus comprises an active tiling system 2, an OASLM 4, and replay optics 6.

The active tiling system 2 comprises a light source 8, for example generated by an argon laser and emitting light passing through a spinning diffuser (not shown). Light 8 may be arranged to impinge on EASLM 12 after being reflected from beam splitter 10. Active tiling optics 14 are provided to direct light modulated by the EASLM 12 to the active tiling (AT) image plane 16. The active tiling optics 14 can include a convex collimation lens 18 and a five-by-five lenslet array 20. The lenslet array 20 is arranged as a two-dimensional grid so that 25 spatially separated images of the EASLM are duplicated in the AT image plane 16 where the OASLM 4 is present. Different arrays including different numbers of lenses can also be used.

OASLM 4 may include a photosensitive layer sandwiched between a pair of glass substrates (e.g., an optical sensor such as amorphous silicon or some other photoconductor) and a bistable liquid crystal light modulation layer. The inner surfaces of the organic substrates have transparent electrodes that can be formed of layers of indium tin oxide (ITO). A pixilated metal mirror (or dielectric stack mirror) can also be provided between the photosensitive layer and the liquid crystal layer, so that the OASLM has a photosensitive surface 22 and an image display surface 24. Upon application of an appropriate voltage to the electrode, any optical image impinging on the photosensitive surface 22 causes the equivalent image to be recorded (ie, loaded) into the liquid crystal material of the image display surface 24.

Patterned electrodes can be formed to define 25 OASLM segments (corresponding to 25 replicated images formed in the AT image plane) to which voltage can be applied independently. Upon applying an appropriate voltage to one of the segments, only that particular segment will be photosensitive and will load the received optical image onto the photosensitive side of the OASLM. Since the OASLM 4 can be located in the AT image plane, the sub-image segments can be sequentially and selectively subjected to photosensitivity (by applying appropriate voltages to each patterned electrode in turn) to construct an image with a very large pixel count. I can have it.

If the application of the device is for stereoscopic imaging, the binarized Fourier transform (FT) of the final desired stereoscopic image can be loaded into the OASLM 4. Thereafter, the stereoscopic image 32 is displayed via the reproduction optics 6. The reproduction optics 6 may comprise a coherent reproduction illumination source 26 which is directed through the beam splitter 28 to the image display surface of the OASLM 4. Thereafter, the three-dimensional image 32 may be formed from the light reflected from the OASLM using a suitable Fourier Transform (FT) lens 30, or an FT mirror (not shown).

OASLM 4 in the AT image plane is disposed within the depth of focus of the AT optics. The AT system is configured to write 6.6 μm pixels in OASLM, where the depth of focus associated with the AT image plane is only about 20 μm. If the OASLM pixel size needed is reduced (e.g., if AT optics are configured to provide a greater amount of demagnification), then a higher density of information can be written to OASLM, so the depth of focus is much higher. Will be found to decrease. The divergence of the light used in the AT system (i.e., the increase angle [theta]) can be increased as the required OASLM pixel size decreases.

Shallow focal depth in devices where very large stereoscopic images are to be displayed may allow many active tiling channels to be used in parallel to produce very large pixel counts in a common AT image plane. A single OASLM or multiple tilted OASLMs can occupy a common AT image plane so that the entire area of the OASLM (which can be close to square meters) is within the 20 μm focal depth of the AT optics. The AT channels themselves may be aligned with one another in the axial direction to create a common focal plane. Therefore, the depth of focus of AT systems places constraints on the design and structure of stereoscopic imaging systems based on AT modulation technology. Systems implemented using very high quality optical components are incredibly expensive.

Referring to Fig. 2, a new image transfer device is shown. Similar reference numerals are assigned to components of the apparatus described with reference to FIG. 2 that are common to the components of the active tiling system described with reference to FIG. 1.

The image delivery device may use a collimated light source 50 to irradiate the EASLM through the beam splitter 10. The first lens 52 of focal length F ₁ and the second lens 54 of focal length F ₂ serve as relay optics and provide a reduction M of F ₁ / −F ₂ . In the nominal image plane 56, there will be a reduced image of the EASLM 12. OASLM can be located several millimeters from the nominal image plane while still producing the required stereoscopic image.

3 illustrates an active tiling system and is described with reference to FIG. 2. The active tiling system of FIG. 3 may include all components of the system described with reference to FIG. 2, and is disposed in the pupil plane of the relay optics to form a Fourier correlator to form a Fourier correlator (DAG) 60. It further includes.

The DAG 60 is configured to generate a 5 × 5 array of diffraction orders from a single input beam, thus generating an array of 25 images or sub-images of the EASLM in the nominal image plane 56. DAG 60 may include, for example, a Dammann grating or a non-separable DAG. Of course, the DAG can be configured to generate different numbers of images or sub-images, including different sized arrays.

Using collimated light can increase the tolerance of OASLM placement in an active tiling system, allowing the active tiling system to have a larger "effective" depth of focus. Therefore, a device using the new active tiling system disclosed herein can significantly reduce design constraints. In dynamic holographic imaging applications where multiple EASLMs are used to tilt the images onto the OASLM, the reduction in performance is due to tilting the OASLM away from the nominal image plane, as shown by the tilted OASLM 62 of FIG. It is not related to losing.

When the collimated light is irradiated to the EASLM, since the OASLM pixel size is reduced (ie, the demagnification power of the active tiling optics is increased), no increase in the divergence of the irradiation radiation is experienced. Therefore, new active tiling techniques can be used more extensively at much lower cost than possible previously considered.

In one embodiment, collimated light may be irradiated to the AT optical system (of the type described above with reference to FIG. 3). Since the OASLM is translated over a certain distance, no visible image degradation of the stereoscopic image occurs. However, when diffused (i.e. divergent) light is irradiated to the EASLM, the allowable OASLM translation depth is completely degraded. In other words, the diffusion survey of EASLM requires that OASLM be located very close to the focal plane of the AT system (eg 201 Am). On the other hand, illuminating collimated light as described herein allows even greater degrees of freedom in OASLM positioning.

4 illustrates an apparatus configured to provide collimated light. In one embodiment, the laser 90 is arranged to provide highly collimated light. In one embodiment, the laser 90 comprises an Adlas laser. The output of the laser 90 is connected to a half-wave plate 92, a polarizer 94, an acoustic-light modulator 96, and a spinning diffuser 98 before collimation by the collimation lens 100. To pass. The device may further comprise a square opening 102.

5 shows an example method for recording information in OASLM. In operation 110, a CGH image is displayed on the spatial light modulator. In operation 120, the collimated light is irradiated to the spatial light modulator. In operation 130, the modulated light produced by the spatial light modulator is directed to the nominal image plane.

Using collimated light to irradiate the spatial light modulator provides the effect of mitigating the accuracy that OASLM needs to be located in the nominal image plane. In operation 140, a plurality of images are formed in the nominal image plane. The optically addressed spatial light modulator may be located in or around the nominal image plane. In one embodiment, the OASLM is inclined with respect to the nominal image plane.

In one embodiment, an image delivery device for recording an image to OASLM is disclosed. The apparatus includes a light source, a spatial light modulator located in the path of light from the light source, and relay optics positioned to receive modulated light from the spatial light modulator. The relay optics are arranged to project the image of the spatial light modulator onto the nominal image plane. The light source is configured to radiate substantially collimated light to the spatial light modulator.

The image delivery device may be configured to generate an image of a computer generated hologram (CGH) displayed by the spatial light modulator in the nominal image plane. The device provides an image with a relatively small "visible" focal depth and the CGH pattern becomes unrecognizable to the eye when viewed at a certain distance (eg, 20 μm or more) from the nominal image plane (moving microscope) See through).

However, it has been found that OASLM can be translated several millimeters away from the nominal image plane of the device while still reproducing stereoscopic images without actually any significant degradation. That is, OASLM can be translated away from the nominal image plane by a much larger distance (by a few orders of magnitude) than expected without affecting the stereoscopic image reproduced by the OASLM.

Thus, there is provided an image containing information necessary for allowing a stereoscopic image to be generated by OASLM, without being a recognizable visible copy of the image displayed on the spatial light modulator. When diffusion irradiation is used instead, the image relayed by the relay optics is out of focus over a certain distance, eg 201 μm, but loss of focus also results in loss of stereoscopic images. OASLM may be located within the nominal image plane of relay optics, or around the nominal image plane. Design tolerances can be relaxed from microns to millimeters.

In one embodiment, the relay optics comprise replication means such that a plurality of images of the spatial light modulator means (eg EASLM) are provided in the nominal image plane. The replicating means may comprise a diffraction array generator (DAG) located in the pupil plane of the relay optics. Providing a replication means, in particular a DAG, may enable two or more images of the spatial light modulator to be formed by relay optics. For example, a DAG may be used that provides replicated images of 5 x 5 error over a nominal image plane.

In one embodiment, the replication means is integrated into active tiling (AT) systems, where the replicated images are directed to OASLM. Portions of the OASLM may be sequentially photosensitive (eg, by using patterned OASLM electrodes or shutters) such that a plurality of successive images in which a high pixel count image such as CGH is displayed on a spatial light modulator From OASLM can be configured. Irradiation of the image may be recorded in the OASLM as a beam of coherent light, where the light is subsequently operated by the optical system. The optical system can be configured to provide a Fourier transform of light in generating a stereoscopic (ie, three-dimensional) image.

The spatial light modulator may be electrically addressable. That is, the elements of the spatial light modulator may be connected to and addressed by an electronic circuit that allows a high speed dynamic image to be generated. In the case of a typical EASLM, the CGH displayed thereby may have spatial frequencies between zero and 77 line pairs per millimeter. CGH can also include portions of larger CGH images.

In one embodiment, the spatial light modulator comprises a liquid crystal spatial light modulator. For example, a liquid crystal electrically addressed spatial light modulator (EASLM) having a thin film transistor (TFT) active back-plane may be used. Various alternative types of EASLM, such as digital micro-minor devices (DMDs), may also be used.

The spatial light modulator may be configured to operate in a reflective mode. Alternatively, the spatial light modulator may operate in a transmission mode. Therefore, different optical configurations can be implemented using either reflective or transmissive spatial light modulators. In one embodiment, the collimated light source comprises a laser. Using a laser allows high optical powers to be provided, which is particularly important where high image replication is required.

In yet another embodiment, the holographic display device includes an image delivery device and an optically addressed spatial light modulator, wherein the optically addressed spatial light modulator is located in or around the nominal image plane. Rather than within the depth of focus of the image delivery device, the image delivery device may record an image in OASLM that is located within a specific range (eg, a few millimeters) of the nominal image plane of the image delivery device.

The holographic display device may comprise a single OASLM or multiple tilted OASLMs. In one embodiment, the image is recorded into OASLM by multiple image transfer devices. OASLM can be tilted with respect to the nominal image plane of the image delivery device without any effect on the quality of stereoscopic images reproduced from OASLM.

The active tiling apparatus and other embodiments described herein can be configured to significantly reduce the tolerance that the OASLM is positioned relative to the nominal image plane. By including multi-channel AT systems, the channels do not need to be axially aligned with each other within a specific distance (eg 20 μm) from each other. Moreover, the OASLM can be mounted at a distance greater than +/- 10 μm from the nominal image plane, for example, rather than within +/- 10 μm. Thus, less mechanical strain is placed on the OASLM, reducing the likelihood of stereoscopic image distortion.

The term light as used herein may be understood to include all ultraviolet (UV) light, visible light and infrared light. Moreover, it can be understood that various optical components can generate various wavelengths or ranges of wavelengths of light.

Although the examples described above relate primarily to an apparatus configured for use in a holographic active tiling system, those skilled in the art will recognize that embodiments may also be applied in many alternative applications.

The above-described system may use dedicated process systems, microcontrollers, programmable logic devices, or microprocessors to perform some or all of the above operations. Some of the operations described above may be implemented in software, while other operations may be implemented in hardware.

For convenience, the operations are described as various interconnected functional blocks or different software modules. However, this is not essential and there may be cases where these functional blocks or modules are equivalently aggregated into a single logic device, program or operations with unclear boundaries. In any event, the features of the functional blocks and software modules or flexible interface may be implemented by themselves or in combination with other operations in either hardware or software.

While the principles have been described and illustrated in the preferred embodiments of the present invention, it should be apparent that the above embodiments may be modified in arrangement and detail without departing from such principles. All changes and modifications that come within the spirit and scope of the following claims are claimed.

Claims (32)

In the device, A light source configured to provide a path of collimated light, the light source comprising a half wave plate 92, a polarizing plate 94, an acoustic-optic modulator 96, and a spinning diffuser 98. The light source; A spatial light modulator (12) positioned in the path of the collimated light and configured to modulate the collimated light; Relay optics 52, 54 configured to receive modulated light from the spatial light modulator 12 and to project a portion of the computer generated image to the optically addressable spatial light modulator 4, wherein the optical Portions of the spatial light modulator 4 which are addressable to are sequentially photosensitive such that the computer image is constructed from a plurality of consecutive images received from one or more spatial light modulators, and the light source receives the collimated light in the spatial space. And configured to irradiate the light modulator (12). The method of claim 1, The relay optics 52, 54 comprise a replication assembly 60 configured to replicate a portion of the computer generated image onto the optically addressable spatial light modulator 4 as a plurality of sub-images. Further comprising the device. The method of claim 2, The replica assembly (60) comprises a diffrative array generator (DAG) located in the pupil plane of the relay optics (52, 54). The method of claim 2, The relay optics are a first lens 52 located on one side of the replica assembly 60 and a second lens 54 located on the side of the replica assembly 60 opposite the first lens 52. Wherein the first lens 52 has a first focal length, the second lens 54 has a second focal length, and the relay optics correspond to a ratio of the first and second focal lengths. And provide demagnification of the computer generated image. delete The method of claim 1, The spatial light modulator (12) comprises an electrically addressable spatial light modulator (EASLM). The method of claim 1, The light source further comprises a laser. delete The method of claim 1, The optically addressable spatial light modulator (4) is inclined with respect to the nominal image plane (56). In the method, Generating a highly collimated light beam from a collimated light source comprising a half wave plate 92, a polarizer 94, an acoustic-light modulator 96, and a spinning diffuser 98; Irradiating the collimated light beam to a spatial light modulator (12); Modulating the collimated light beam; And Directing the modulated light to an optically addressable spatial light modulator (4). 11. The method of claim 10, Duplicating said modulated light beam as a plurality of images formed on said optically addressable spatial light modulator (4). The method of claim 11, wherein Wherein the optically addressable spatial light modulator (4) is inclined with respect to the nominal image plane (56). The method of claim 11, wherein Illuminating the modulated light beam to the optically addressable spatial light modulator (4) to form a three-dimensional image. The method of claim 11, wherein The spatial light modulator (12) operates in a reflective mode. The method of claim 11, wherein The spatial light modulator (12) operates in a transmission mode. In the system, Means for generating a highly collimated light beam from a collimated light source including a half wave plate 92, a polarizing plate 94, an acoustic-light modulator 96, and a spinning diffuser 98; Means for irradiating the collimated light beam to a spatial light modulator (12); Means for modulating the collimated light beam; Means for directing the modulated light beam to an image display, wherein the computer generated image is constructed from a plurality of consecutive images displayed on the image display by one or more spatial light modulators Way; And Means for reflecting light from the image display to form a three-dimensional image corresponding to the computer generated image. 17. The method of claim 16, And means for focusing the modulated light on the image display located at least one millimeter outside of the nominal image plane (56). 17. The method of claim 16, Means for maintaining a constant depth of focus of the system, regardless of the pixel density of the image display. 17. The method of claim 16, And means for maintaining a constant depth of focus of the system regardless of the angle of inclination of the image display relative to a nominal image plane (56). 20. The method of claim 19, And the means for irradiating the collimated light beam to the spatial light modulator (12) further comprises a laser. A computer readable medium having stored thereon instructions, wherein the instructions are executable by the at least one device such that the at least one device performs operations. The operations are Generate a highly collimated light beam from a collimated light source comprising a half wave plate 92, a polarizer 94, an acoustic-light modulator 96, and a spinning diffuser 98, Irradiates the collimated light beam onto the spatial light modulator 12, Modulating the collimated light, Directing the modulated light beam to an optically addressable spatial light modulator (4), wherein portions of the optically addressable spatial light modulator (4) are characterized in that a computer image is received from a plurality of spatial light modulators. And are sequentially sensitized to be constructed from a plurality of consecutive sub-images. 22. The method of claim 21, The operations further comprise irradiating the optically addressable spatial light modulator (4) with the read light to form a three-dimensional image. 22. The method of claim 21, The spatial light modulator (12) comprises an electrically addressable spatial light modulator. 22. The method of claim 21, And the collimated light source further comprises a laser. 22. The method of claim 21, The operations are Diffracting the modulated light into an array comprising a plurality of consecutive sub-images, Directing each of the plurality of consecutive sub-images onto the optically addressable spatial light modulator (4). 26. The method of claim 25, The modulated light is diffracted by a diffraction array generator (DAG), and the plurality of successive sub-images are directed by relay optics 52, 54, the DAG of the relay optics 52, 54. A computer readable medium located in the pupil plane. 27. The method of claim 26, The focal depth of the relay optics (52, 54) remains constant regardless of the angle of inclination of the optically addressable spatial light modulator (4) with respect to a nominal image plane (56). 28. The method of claim 27, And the focal depth is at least one millimeter. 11. The method of claim 10, Generating a computer-generated holographic image on the optically addressable spatial light modulator 4, wherein the computer-generated image is arranged by the plurality of spatial light modulators to the optically addressable spatial light modulator. And a plurality of successive images displayed on (4). 30. The method of claim 29, The sequentially photosensitive portions of the optically addressable spatial light modulator (4) are displayed as the plurality of images. 17. The method of claim 16, The means for generating the highly collimated light beam further comprises a square opening (102). 17. The method of claim 16, The means for generating the highly collimated light beam further comprises a collimating lens (100).

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